This portable home power backup system also provides automatic transfer of power during outages. Combining a generator, a smart transfer switch, and battery backup, the HP2S line installs on a home’s pre-selected emergency system (lights or appliances), and the switch automatically transfers power to that system. It’s available in four versions. Cost: $4,500 to $5,000. Honda Power Equipment. 800-426-7701. www.honda.com.